Electric heater.



I'. P. MIES.

ELECTRIC HEATER.

APPLICATION FILED JAN. 1o, 1910.

1,QM3 8,4E10c Patented sept. 1o, m2.

iii

UNITED sTaTEs PATENT oEEicE.'

FRANK 1. MIES, OF CHICAGO, ILLINOIS, ASSIGNOR TO PLURAL SYSTEM VENTLATR C0.

ELECTRIC HEATER.

Specification of Letters Patent.

Patented Sept. 10, 1912.

To all whom t may concern:

Be it linown thatV I, FRANK E. MIES, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Elect-ric Heaters, ofy

which the following is a specification. y

My invention-relates to improvements in thermo-electric devices and more particularly to devices of this character designed to heat air that may be brought into contact with' the surfaces thereof.

One of the objects of my invention is to provide an electric air-heating device having a maximum of surface of the heating medium presented to the direct action of the air.

Another object of my invention is to provide air-heating device wherein the surface ofthe heating medium is increased substantially in proportion as expansion of the air is increased due to the increased temperature thereof, as the air passes through the device.

Still another object cf my invention is to provide a device of the character described that is highly eiicient, cheap in construction, durable, and not deranged by eapansionof the` heating medium.

Other and further objects of my invention will become apparent to persons skilled in the art from the description' and drawings, in whichw f Figure 1 is an elevation of one of my heating units with part of the casing broken away to show the heating medium; Fig. 2' is an enlarged elevation showing a fragment of the heating medium on one side of the .vertical axis partly in section; Fig. 3 is a cross sectional view'taken on line 3-3 of Fig. 2; Fig. 4'is a fragmentary sectional view taken on l1ne 4-4 of Fig. 8; and Fig.

f 5 is aI section on line 5 5 of Fig. 4.

In all of the views the same reference characters indicate similar parts.

The heater consists of a'continuous electric conductor, such as va wire, ribbon, or similar heating medium wound upon substan-A tial supports and providing spaces for free circulation of air in cont-actwith a maximum surface of the heating medium.y The general form of the device is thatv of' a truncated cone, as shown in Fig. 1, the heating medium being contained Within a casing open at each end.

,f ith a minimum of material.

in the embediment illustrated, io is the yupper supporting struct-ure consisting of a plurality of concentric rings, 11, 12, v13, and 14. The lower supporting structure l5 is of similar but larger diameter composed of rings, 16, 17, 18, and 19. The rings of each structure are held together by interconnecting radial arms, 20. -The rings are preferably -made of some insulating and substantially non-combustible material, such as enameled iron. The rings are notched, as shown at 21, at intervals for the reception of the wire-bearing supporting parts 22. The wire-bearing supports are provided wit-h a series of lateral grooves, 23, for receiving and retaining individual wires. The bars 22 are provided with ribs, 24, to give strengtlil The ribs are notched, near each end, as at 25, for the reception of the' respective rings, lll-15. The rings and supporting bars are preferably made of iron and then covered with an enamel so that any wires wound thereon will not come into metallic contact with the supporting structure. l

vThe rings, 10 and 15 are securely fixed a proper distance apart. The bars of the inner ring, of which there is vshown to be six, are laid in place so that the notches in said hars will fall in the notches in said rings. The rings and bars are thereby held against lrelative axial movement, as plainly shown.

The heating medium or wire, 26, is then wound tightly over said hars and in the lateral grooves, 23, provided therein. These grooves are as close together as may be to prevent contact of adjacent turns of the wires. When the wires are wound around the bars, they are thus prevented from moving radially and being restrained from movement in other directions, by thil notches, they are firmly retained in place. After one layer of wire has beenwound in the grooves of the inner series of. bars, another series of bars are placed in the notches of the ring, 12, and the heating medium wound around them in the same manner. In turn the bars are thus secured to rings 13 and 14. The heating medium may thus be wound around all of the bars without severing said medium and all of the bars will thereby be securely held in place. The

grooves 23 are sufficiently deep to retain thel panded by the application of heat. 26

Q v nesecito 26h, the ends of the heating medium, torna the electrical terminals ofthe device. 'llheir terminals inay be arranged for ready conn nection to the circuit in anyg convenient manner, rlhe heating medium thus described may be contained Within a jacket or casing, 27, and when air is forcibly pro jected through the device, `it should preterably enter the smaller end and leave at the larger end,a

When the air is cool, it occupies smaller space than When expanded by the heat and as the air passes through the device the cross section of its path correspondingly increases Withl the increase of temperature and the supercial area of the heating inediuin increases as the air progresses toward the larger end, By this means the air is conned and retained in Contact with the heating medium and the resistance to its movement through the device is retained at a ininin'iumo p When natural circulation is to be depended upon to move the air through the device, the larger end should be above and `the smaller end belovrB The air as it becomes heated Will move out land upwardly from the larger end and colder air v/ill be drawn into the smaller end, thereby forming a stronginduced draft ot air.. l

'llhe moving air through" the' device will come in contact with practically the entire surface ot the .heating medium and will absorb most of its heat directly therefrom, but as the air also comes in contact with all out the supporting structure it will absorb the heat that may be imparted to such structure by the heating medium.

While l have thus described in sorne detail a single embodiment oit my invention, it Will be understood that such particular embodinient is only one which ll have chosen troni numerous others as the preferred construction, and l do not, therefore, limit my in vention to the precise struct-ure described the peripheries thereof, and a contilniousl unbroken Wire Wound successively upon' the dll concentric truncatedcone strnctures so formed, A

2. lin a heating device et trance-telecine l shape, an upper and a lower structure each 'having a plurality of concentric rings and radial connecting arnis, the rings of the lower structure being greater in diameter than corresponding rings of the upper structure, separable interchangeable bars 'having notches near their ends, said rings having on their outer edges enacting notches at frequent intervals around their peripheries, whereby bars may' he placed upon the innermost rings of both upper and lower structure, held vertically rby said enactingnotch engagement and radially by Wire to ,be Wound therearound to constitute a heat- Qing medium, successive rings subsequently to be siniliarly connected by bars the Vbars similarly bound by Wire, and a lwire so .Wound upon the device to torni concentric, truncatednone shaped, heating members in'- cluded in thespace defined by the ring of largest diameter.,

ln testimony Wh'ereotl l hereunto set my hand in the presence of two Witnessesn liti/lidi@ ittllllt ln the presence oil- Vif. Linn ALLEN, Meer l?, ALLEN, 

